The present invention relates to a multiposition valve for use in fluid lines containing filters in order to backflush the filter. Such valves are widely used in water irrigation systems having filters for removing solid particles from the water, which filters are periodically cleaned by a backflushing operation.
The presently available backflush valves usually include a housing having an inlet port connectable to the inlet line supplying the pressurised fluid (e.g., water), an outlet port connectable to the outlet line containing the filter, and a backflush port for discharging the dirt from the filter during a backflushing operation. Such valves also include a first passageway interconnecting the inlet port and the outlet port, a second passageway interconnecting the outlet port and the backflush port, and a displaceable valve member movable either to a filtering position to effect a filtering operation wherein the inlet port is connected to the outlet port via the first passageway, or to a backflushing position to effect a backflushing operation wherein the outlet port is connected to the backflush port via the second passageway.
A main disadvantage of the presently available backflush valves, however, is that they waste considerable quantities of clean water through the backflush port. Thus, they normally operate by first connecting the backflush port to the outlet port, and then disconnect the inlet port from the backflush port.
An object of the present invention is to provide a backflush valve having advantages in the above respects.